Quality of Reduction of Posterior Malleolar Fractures: A CT-Based Case-Control Study Comparing AP-PA Screw Fixation vs Posterolateral Approach

Abstract

Category: Trauma; Ankle Introduction/Purpose: Classically, the standard of care in posterior malleolar fracture consisted in indirect reduction and percutaneous anteroposterior (AP) or posteroanterior (PA) fixation. There is a current trend to use a posterolateral approach (PL) for direct visualization of the fragment to obtain superior anatomical reduction. Comparative studies between both strategies of management have usually benefit the PL approach for obtaining superior articular reduction. Nonetheless, most of these studies are retrospective and tend to compare different group of fractures since percutaneous AP or PA groups are usually used for smaller fragments and PL for bigger PM fractures. There are no radiologic studies comparing the quality of reduction of AP-PA screws versus direct PL fixation on similar fracture-specific morphology and size patterns. Methods: A retrospective case-control study was performed including 228 trimalleolar ankle fractures treated in a level 1 trauma center between 2012 and 2021. Demographic and clinical data was obtained. Fractures were classified using the Bartonicek and Rammelt classification. The study group was conformed by 27 patients with PM fractures fixed with percutaneous AP-PA screws (PER). The control group was conformed by 27 patients matching the study group in terms of type of fracture morphology and age treated using a posterolateral approach (PL). Post operative ankle CT images were analyzed and quality of reduction was evaluated in both groups. Quality of reduction was defined according to the articular step-off, graded as excellent (less than 1 mm), satisfactory (1 to 2 mm) or poor (more than 2 mm) in sagittal and axial planes. Differences between groups was evaluated using Fisher's test with statistical significance defined as p <0.05 using SPSS V24.0 analysis software. Results: The average age of both groups was 44.4 years old with 53% of patients being females. According to Bartonicek and Rammelt classification, 2 patients were graded as type 1, 21 as type 2, 3 as type 3 and 1 as type 4. In the PL approach group, the tibio talar reduction was described as excellent in 19 patients, satisfactory in 7 and poor in 1 patient, while the fibular notch reduction was described as excellent in 20 patients, satisfactory in 6 and poor in 1 patient. In the PER group, the tibiotalar reduction was described as excellent in 22 patients and satisfactory in 5, with no patients with poor reduction. The fibular notch reduction was described as excellent in 25 patients, with 1 patient each with satisfactory and poor reduction. No significant difference (p= 0.52) in the articular reduction quality was detected considering the classification mentioned and the demographics variables. Conclusion: In this case-control study there were no significant differences regarding quality of reduction in morphologically matched displaced PM fractures fixed with AP-PA screws versus a PL approach. Further clinical prospective studies are needed to define the clinical relevance of these results and define the optimal strategy of fixation.